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TEM, HREM, L-TEM Studies of Fe-Based Soft Magnetic Melt-Spun Ribbons Subjected to Ultra-Rapid Annealing Process

Maziarz Wojciech, Kolano-Burian Aleksandra, Kowalczyk Maciej, Błyskun Piotr, Chulist Robert, Czaja Paweł, Szlezynger Maciej, Wójcik Anna

Archives of Metallurgy and Materials

2023

Vol. 68, iss. 3

1165--1170

In the present work, we performed the ultra-rapid annealing (URA) process for amorphous Fe78Ni8B14 melt-spun ribbons in order to obtain fine excellent microstructure assuring the best soft magnetic properties. Several microscopic methods mainly based on transmission electron microscopy (TEM) and Lorentz TEM (L-TEM) were applied for detailed studies of the microstructure and magnetic domains structure. The investigation revealed that the optimized parameters of the URA process (500°C/0.5-5 s) lead to outstanding soft magnetic properties. A mixture containing close to 50% amorphous phase and 50% α-Fe nanocrystals of size up to 30 nm has been already obtained after annealing for 3 s. These annealing conditions appear to be the most suitable in terms of microstructure providing the best magnetic properties.

Structural Characterization and Properties of Al/Fe Multi-Layer Composites Produced by Hot Pressing

Kowalski Wojciech, Paul Henryk, Mania Izabela, Petrzak Paweł, Czaja Paweł, Chulist Robert, Góral Anna, Szlezynger Maciej

Archives of Metallurgy and Materials

2023

Vol. 68, iss. 1

137--144

This study aimed to develop Fe/Al multilayered metallic/intermetallic composites produced by hot pressing under an air atmosphere. Analyses were carried out on the composite plates made up of alternatively situated sheets of AA1050 aluminum alloy and DN04 low carbon steel, which were annealed at 903 K for 2, 5, and 10 h. Annealing was performed to obtain reaction layers of distinct thickness. The samples were examined using X-Ray diffraction and scanning and transmission electron microscope equipped with an energy-dispersive X-Ray spectrometer. To correlate the structural changes with mechanical properties, microhardness measurements in near-the-interface layers were performed. All the reaction layers grew with parabolic kinetics with η-Al5Fe2 intermetallic phase as the dominant component. After annealing for 5 and 10 hours, a thin sublayer of θ-Al13Fe4 phase was also detected.

Effect of upgraded field assisted sintering technology on microstructure of NiAl/CrB2 composites

Szlezynger Maciej, Maj Łukasz, Pomorska Małgorzata, Morgiel Jerzy, Jach Katarzyna, Rosinski Marcin

Composites Theory and Practice

2020

R. 20, nr 1

7--10

The method of fabricating metal matrix composites plays a crucial role in obtaining dense materials characterized by high wear resistance. The present work describes an attempt to produce NiAl/CrB2 composites using the next generation spark plasma sintering (SPS) method, i.e. upgraded field assisted sintering technology (U-FAST) technique. Microstructure characterization was performed by means of scanning (SEM) and transmission (TEM) electron microscopy. The SEM microstructure investigations of the NiAl model material proved practically full densification of the material sintered at 1200°C and 1300°C, even if remnants of surplus nickel were observed at the boundaries of rounded NiAl grains. The NiAl/CrB2 composites, besides fused NiAl and CrB2 grains, showed the presence of a raised level of nickel also at the grain boundaries. The TEM microstructure observations helped to establish that even if the grain boundaries were pinned by nickel-rich precipitates, some increase in grain growth took place, as evidenced by the fact that strings of smaller precipitates were also visible outside the matrix grain boundaries. All these microstructure investigations indicate that the newly elaborated U-FAST technique is evidently capable of producing compacts free of porosity at lower temperatures and during a shorter time than solid hot pressing or vacuum sintering in a semiliquid state.